As a technique for improving the quality of images captured by image capturing devices, the following technique disclosed in Japanese Patent No. 4281453 is known. Each pixel in an input image is classified into any of a plurality of classes based on the image pattern of a block including the pixel, and the block is convolved with a coefficient learned from the class of pixels thus classified. Through this process, the image quality is improved correspondingly to the image pattern of the block.
Because pixels in an image captured by an image capturing device deteriorate differently depending on the position of the pixel, it has been difficult to improve an image quality using such a process that is based on the image pattern of a block.